Preparation, characterization, and application of an eco-friendly sand-fixing material largely utilizing coal-based solid waste

The resource utilization of coal-based solid waste (CBSW) is an urgent problem needed to be addressed. This study was based on the principle of intermediate-calcium system to prepare a self-degradable eco-friendly sand-fixing material (SFM) by using CBSW and aeolian sand as main raw materials, and its hydration mechanism and environmental characteristics were investigated. The hydration products of SFM were characterized by XRD, TG-DSC, FTIR, and SEM, and the environmental friendly performances were discussed by leaching test. The results show that the compressive strength of SFM reached 12.4 MPa after 28d when the (CaO + MgO)/(SiO₂+Al₂O₃) was 0.75. After 150 freeze-thaw cycles, the recorded strength was 8.82 MPa which met the international standards but it get completely degraded into powders after 200 freeze-thaw cycles. The leaching test results indicated that the heavy metals in raw materials were solidified; the SFM before and after complete degradation were all eco-friendly. The main hydration products of SFM were ettringite, C-S-H and C-A-S-H, which play an important effect in strength development and solidification of heavy metals. At the same time, the pilot-scale test would reach the similar results. This work provides an effective solution of resource utilization of CBSW and improving the eco-environment of the desert.